The accumulation of medical evidence in recent years regarding the adverse health implications of high fat diets, principally heart attacks, arteriosclerosis and obesity, has caused consumers to become extremely concerned about their diets. It is estimated that between 70-80% of U.S. adult females follow a weight reducing diet at least once a year. Men are also concerned about their weight and cholesterol levels.
Common obesity is currently one of the most prevalent metabolic problems in the general population. Fats and oils are necessary for balanced nutrition. However, the average consumer simply consumes more than is needed for proper nutrition. It is estimated that lipids constitute about 40% of the total calories in the typical western diet. Fats are consumed directly in meats, spreads, salad oils, and in natural produce such as nuts and avocados. Fats and oils are also consumed as a result of absorption or incorporation in foods during baking and frying. The sharp increase in consumption of fast foods is a major contributor to the increase in the amount of dietary fat since fast foods rely extensively on frying processes employing fats and oils. In addition, the snack food industry uses large amounts of fats and oils in the production of potato chips, corn chips and other snack items.
It is clear that there is an enormous potential market for a fat substitute or fat mimetic that is substantially non-digestible or has reduced caloric value. Replacement of fats in the diet with non-caloric substitutes is a more efficient way of reducing caloric intake than replacing sugar or carbohydrates because, gram for gram, the substitution of non-caloric fat substitutes is more than twice as effective as reducing carbohydrate content with substances such as saccharine or aspartame.
One of the difficulties in eliminating fat from the diet is the fact that fats and oils are all-pervasive in food products. In part, this is because they play an important role in the organoleptic acceptability of food products. Generally speaking, a fat substitute providing fewer calories than a conventional triglyceride must be non-digestible, that is, not hydrolyzed in the digestive tract. In addition, it should not be directly absorbed through the intestinal wall. While some types of fat substitutes may be non-digestible, they are not of sufficiently high molecular weight to prevent them from being absorbed through the intestinal wall. The threshold molecular weight of non-absorbability for lipophilic molecules appears to be about 600.
In addition, the fat substitute must itself be non-toxic at high levels of ingestion. It must contain no toxic residues or impurities. To the extent that a fat substitute may be partially hydrolyzed in the digestive tract, any hydrolysis products must be non-toxic and/or metabolizable. If metabolizable, they should have very low caloric value. In general, fat substitutes must be without any serious physiological side effects.
The fat substitutes must also have good organoleptic qualities of mouth feel and must not unacceptably alter the taste of a food composition. In addition, fat substitutes must have appropriate physical properties for use in food compositions. For example, they should be liquids or solids depending on whether they are to be used as oil or shortening substitutes and, where used for cooking, must be thermally stable.
A prominent disadvantage of certain of the non-digestible or non-absorbable fat substitutes which have been developed to date is the tendency for such substances to promote an undesired laxative effect when ingested at relatively high levels in the diet. Since these fat substitutes are not altered by or removed from the gastrointestinal tract, they remain in an oil-like physical state and thus tend to promote anal leakage or short bowel transit times due to their lubricant properties and general immiscibility with the aqueous components of the diet. This problem has been addressed in the past by using "anti-anal leakage agents" in combination with the fat substitute. Such anti-anal leakage agents (e.g., silica, cellulose fiber) may undesirably alter the mouth feel and organoleptic properties of the food composition, however.
It is apparent, therefore, that there is a need for an improved low calorie edible oil substitute that has the properties of a triglyceride oil when formulated into food compositions but which is altered upon ingestion to a less "oil-like" physical state and which does not need to be used in conjunction with an anti-anal leakage agent. A fat substitute having these characteristics would likely enjoy greater consumer acceptance than many of the currently known mimetics.